Usually this error is a result of some part of the upgrade process not migrating the configuration correctly. To fix this issue, the best solution is usually to perform a clean install and restore the backup with no configuration.
Hope this helps!
We looked at the code, and that error message is really triggered solely on the data engine allocation, independent of any worker configuration. Is there really a data engine defined in your configuration? You might need to add a data engine host first, then add your new worker.
I ended up with several underlying issues causing a variety of problems, so I did a clean re-install. Following the clean re-install, there were several other issues that I addressed below:
First, IIS was installed on both the primary and worker servers. After restarting the server, it seemed that Tableau Server and IIS were competing for port 80, and which ever one grabbed port 80 first won. So, I uninstalled IIS.
Second, Tableau was generating a random port to verify licensing. Windows firewall did not like this. So, for the time being, I have turned off the firewall on both the primary and workers.
While, I will eventually want to turn the firewall back on, I do now have Tableau Server (7.05) configured with High Availability/Failover.